Swiss J Geosci (2013) 106:505–527 DOI 10.1007/s00015-013-0150-8 Provenance of the Upper Cretaceous to Eocene Gosau Group around and beneath the Vienna Basin (Austria and Slovakia) Gerald Stern • Michael Wagreich Received: 18 December 2012 / Accepted: 23 September 2013 / Published online: 22 October 2013 Ó Swiss Geological Society 2013 Abstract Chemistry of detrital garnets, chrome spinels Keywords Eastern Alps Á Western Carpathians Á and tourmalines of 30 selected samples in combination Heavy mineral analysis Á Detrital garnet Á with the general heavy mineral distribution from 523 Detrital chrome spinel Á Electron microprobe sandstone samples of the Upper Cretaceous to Eocene Gosau Group of the eastern part of the Eastern Alps and the western West Carpathians result in an advanced picture of 1 Introduction sedimentary provenance and palaeogeographic evolution of that area. Garnets from Coniacian to Campanian sediments The well documented sedimentation history of the Upper are partly derived from a metamorphic sole remnant of Cretaceous to Paleogene Gosau Group as part of the Neotethys ophiolites to the south. Tectonically high Northern Calcareous Alps (NCA) reflects ongoing tectonic ophiolitic nappes, later on completely eroded, supplied processes at the active margin of the Austroalpine micro- mainly the paleogeographically southern Gru¨nbach and plate during the Late Cretaceous (e.g. Wagreich 1993a; Glinzendorf Gosau basins with ultramafic detritus, repre- Faupl and Wagreich 2000). Several studies of heavy min- sented by chrome spinels of a mixed harzburgite/lherzolite eral assemblages contributed significantly to the composition, whereas no direct indications for a northern understanding of detrital sources and hence the paleogeo- ophiolitic source, the Penninic accretionary wedge to the graphic evolution of that area, including the NCA, during north of the Gosau basins, could be found. In the younger the Late Cretaceous to Paleogene (Woletz 1967; Faupl part of the Gosau basins fill, from the Maastrichtian to the 1983; Stattegger 1986, 1987; Winkler 1988; Wagreich and Eocene, only almandine-rich garnets could be observed Marschalko 1995). However, reconstructions of prove- suggesting a southern provenance from low-grade meta- nance are still puzzling and paleogeographic positions or morphic metapelites of exhuming Austroalpine correlations of various Gosau basins at the transition zone metamorphic complexes. Ophiolite detritus is reduced in between the Eastern Alps and the Western Carpathians are the Maastrichtian and disappears in the Paleogene. still under debate (e.g. Wagreich and Marschalko 1995; Hofer et al. 2013). In such a case, single grain chemistry of heavy minerals provides an important tool in provenance Editorial handling: W. Winkler & A. G. Milnes. analysis techniques (e.g. Henry and Guidotti 1985; Pober and Faupl 1988; Morton 1991; Von Eynatten and Gaupp Electronic supplementary material The online version of this article (doi:10.1007/s00015-013-0150-8) contains supplementary 1999; Weltje and Von Eynatten 2004; Mange and Morton material, which is available to authorized users. 2007; Meinhold et al. 2009; Aubrecht et al. 2009) but so far this was only applied selectively to the Gosau Group & G. Stern ( ) Á M. Wagreich (Pober and Faupl 1988). The present study gives an Department of Geodynamics and Sedimentology, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria updated overview of Gosau Group heavy mineral assem- e-mail: [email protected] blages in the eastern part of the Eastern Alps and the M. Wagreich western part of the West Carpathians using published and e-mail: [email protected] new data, and gives new insights from single grain 506 G. Stern, M. Wagreich chemistry with the goal to improve the provenance concept 3 Stratigraphy and to reconstruct the paleotectonic evolution of these areas during Late Cretaceous to Paleogene times. 3.1 Gießhu¨bl basin Strata of the Gießhu¨bl basin (Coniacian to Palaeocene), 2 Geological setting which is part of the Bajuvaric Nappe system (Lunz Nappe; Faupl and Wagreich 1996) of the NCA and overthrusted by The Gosau Group of the NCA comprises Upper Cretaceous the Tirolian nappe system, starts with shallow-marine to Paleogene sediments overlying folded and faulted sandstones and breccias of Coniacian/Santonian age. The Permian to Lower Cretaceous units (Wagreich and Faupl overlying Upper Santonian–Campanian to Lower Maas- 1994). The NCA itself can be subdivided into several thrust trichtian Nierental Formation (Wessely 2006) is already units, from base (north) to top (south), including the Ba- attributed to the Upper Gosau Subgroup and comprises juvaric, Tirolic and Juvavic (or higher) nappe units mainly calcareous marls of a pelagic to hemipelagic slope according to the classical concepts (e.g. Mandl 2000; facies (Krenmayr 1999; Wagreich and Krenmayr 2005; Schmid et al. 2008). The Gosau Group can be subdivided Wagreich et al. 2011). The main part of the Gießhu¨bl basin into a fluvial, lacustrine to shallow-marine Lower Gosau fill is represented by the Gießhu¨bl Formation (subdivided Subgroup (Turonian to Santonian/Campanian, in some into a Lower, Middle and Upper Gießhu¨bl Member), a areas up to Maastrichtian), and a deepwater dominated massive, deep-water turbidite to mass-flow-complex, Upper Gosau Subgroup, locally starting in the Upper deposited below the calcite compensation depth (Faupl and Santonian and reaching the Eocene as defined by Faupl Sauer 1978; Wagreich 2001a), with a temporal extent up to et al. (1987), Wagreich and Faupl (1994) and Faupl and the Thanetian (Wessely 1992). Gosau Group sediments of Wagreich (1996). Gosau Group sedimentation started in the Gießhu¨bl basin are reported from below the Neogene of local basins (e.g. Sanders 1998; Wagreich and Decker the Vienna Basin (Wessely 2006) and crop out in the areas 2001), giving way to larger and more widespread sedi- of Gießhu¨bl, Alland and Altenmarkt (Fig. 1). Equivalents mentation in the Upper Gosau Subgroup (Wagreich 1993a; of the Gießhu¨bl basin are exposed around Lilienfeld, where Krenmayr 1999; Wagreich et al. 2011). the Gosau Group comprises Coniacian–Santonian Lower Various Gosau Group deposits are exposed in the Gosau Subgroup units followed by the hemipelagic–pela- easternmost part of the Eastern Alps (Austria) in the area gic Nierental, Spitzenbach and Gießhu¨bl Formations of the of Gießhu¨bl near Vienna and Gru¨nbach at the south- Campanian to Maastrichtian (Wagreich 1986; Wagreich western margin of the Vienna Basin as well as in the et al. 2011). westernmost part of the West Carpathians at the area of The Prottes Gosau Group (Coniacian to Palaeocene) is a Brezova´ and Myjava, Slovakia (Fig. 1; see also Wagr- small, isolated, mainly conglomeratic subcrop complex eich and Marschalko 1995). Beneath Neogene sediments transgressing the Mesozoic of the Tirolic nappes from of the Vienna Basin, NE–SW-striking Gosau Group underneath the Neogene of the Vienna Basin at Prottes to deposits can be traced over several wells down to depths outcrops at Altenmarkt (Wessely 2006). of more than 4,000 m (Wessely 1993; Zimmer and Wessely 1996). During the post-Eocene Alpine orogeny, 3.2 Gru¨nbach basin sediments of the Gosau Group were folded and are today arranged in structurally complex synclines on different The Gru¨nbach basin (Santonian to Palaeocene) is situated tectonic nappes of the NCA and the Carpathians (Fig. 1). at the south-western margin of the Vienna Basin, mainly on From north to south the Gießhu¨bl Syncline, the Prottes Tirolic units in the area of Gru¨nbach—Neue Welt (Plo¨ch- Gosau Group, its Slovakian equivalents at Studienka inger 1961; see Fig. 1). The connection to Upper below the Neogene Vienna Basin fill, and Brezova´- Cretaceous rocks beneath the Neogene fill of the Vienna Myjava (here for convenience summarized as Slovakian Basin is controversial (e.g. Hofer et al. 2011). The base of Gosau basin), the Glinzendorf Syncline and the Gru¨n- the Gru¨nbach Gosau Group comprises Upper Santonian red bach Syncline have been defined (Plo¨chinger 1961; conglomerates and breccias of alluvial fan environments Wessely 1974, 1984, 1992, 1993, 2000, 2006; Zimmer (Kreuzgraben Formation; e.g. Erkan 1972; Summesberger and Wessely 1996). These various Gosau Group occur- et al. 2002). A transgressive trend is documented by the rences are interpreted as four, partly separated basins at overlying shallow-marine Maiersdorf Formation that con- least during deposition of the Lower Gosau Subgroup tains calcareous breccias, minor sandy limestones (Wagreich and Marschalko 1995; Wagreich and Decker (including corals, brachiopods and gastropods) and reef- 2001). We therefore refer to these various Gosau basins forming rudist limestones (Summesberger et al. 2002). The in the following sections. limnic to marginal-marine Gru¨nbach Formation of the Provenance of the Gosau Group 507 Fig. 1 Simplified geological map of the eastern part of the Eastern and Marschalko 1995; Zimmer and Wessely 1996). Sampled Alps, the pre-Neogene basement of the Vienna Basin, and the western locations of wells and outcrops are marked with stars, with the part of the West Carparthians, with Gosau Group situated at the sample numbers (Table 1). Suggested nappe structure of the NCA border of (in the Northern Calcareous Alps), and underneath, the subcrops are slightly modified after Wessely et al. (1993). BN Neogene Vienna Basin (modified after Wessely et al. 1993; Wagreich Bajuvaric nappes, TN Tirolic Nappes, HN higher NCA nappes Lower Campanian contains coal layers within marls and 3.3 Glinzendorf basin fine-clastic sandstones as well as a massive conglomerate horizon (Summesberger et al. 2002; Wessely 2006) and is Because of the limnic to shallow-marine character with comparable to units at the base of the Glinzendorf Syn- interbedded coal horizons of the Glinzendorf basin (San- cline. With the Upper Campanian to Maastrichtian Piesting tonian to Campanian or maybe Maastrichtian strata on Formation the facies changed to deeper-marine neritic In- Tirolic nappes below Neogene sediments), the Glinzendorf oceramus marls and Orbitoides-bearing sandstones Syncline is sometimes interpreted as an easterly continua- (Hradecka´ et al.